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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 20 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 586 + 157? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 68 × 90? (a) 63000 (b) 6300 (c) 630
  3. 3.Best estimate of 164 + 463? (a) 500 (b) 900 (c) 700
  4. 4.Best estimate of 293 + 686? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 59 × 36? (a) 2400 (b) 24000 (c) 240
  6. 6.Best estimate of 264 + 256? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 467 + 373? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 62 × 31? (a) 18000 (b) 180 (c) 1800
  9. 9.Best estimate of 445 + 302? (a) 500 (b) 700 (c) 900
  10. 10.Best estimate of 756 + 388? (a) 1200 (b) 1400 (c) 1000
  11. 11.Best estimate of 66 × 46? (a) 350 (b) 35000 (c) 3500
  12. 12.Best estimate of 87 × 23? (a) 180 (b) 18000 (c) 1800
  13. 13.Best estimate of 33 × 28? (a) 900 (b) 9000 (c) 90
  14. 14.Best estimate of 74 × 90? (a) 63000 (b) 6300 (c) 630
  15. 15.Best estimate of 26 × 80? (a) 2400 (b) 240 (c) 24000
  16. 16.Best estimate of 261 + 332? (a) 800 (b) 600 (c) 400
  17. 17.Best estimate of 13 × 36? (a) 4000 (b) 40 (c) 400
  18. 18.Best estimate of 56 × 16? (a) 12000 (b) 1200 (c) 120
  19. 19.Best estimate of 31 × 29? (a) 9000 (b) 90 (c) 900
  20. 20.Best estimate of 67 × 32? (a) 210 (b) 21000 (c) 2100
  21. 21.Best estimate of 52 × 98? (a) 500 (b) 50000 (c) 5000
  22. 22.Best estimate of 416 + 298? (a) 900 (b) 700 (c) 500
  23. 23.Best estimate of 61 × 34? (a) 1800 (b) 18000 (c) 180
  24. 24.Best estimate of 50 × 56? (a) 30000 (b) 3000 (c) 300
  25. 25.Best estimate of 653 + 206? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 699 + 636? (a) 1100 (b) 1500 (c) 1300
  27. 27.Best estimate of 164 + 720? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 12 × 96? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 59 × 17? (a) 1200 (b) 12000 (c) 120
  30. 30.Best estimate of 618 + 427? (a) 800 (b) 1000 (c) 1200
  31. 31.Best estimate of 67 × 83? (a) 560 (b) 5600 (c) 56000
  32. 32.Best estimate of 47 × 56? (a) 3000 (b) 300 (c) 30000
  33. 33.Best estimate of 20 × 93? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 826 + 225? (a) 800 (b) 1200 (c) 1000
  35. 35.Best estimate of 463 + 530? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 43 × 70? (a) 2800 (b) 28000 (c) 280
  37. 37.Best estimate of 89 × 41? (a) 3600 (b) 360 (c) 36000
  38. 38.Best estimate of 637 + 841? (a) 1200 (b) 1600 (c) 1400
  39. 39.Best estimate of 754 + 605? (a) 1600 (b) 1400 (c) 1200
  40. 40.Best estimate of 19 × 54? (a) 10000 (b) 100 (c) 1000

Answer key

  1. 800
  2. 6300
  3. 700
  4. 1000
  5. 2400
  6. 600
  7. 900
  8. 1800
  9. 700
  10. 1200
  11. 3500
  12. 1800
  13. 900
  14. 6300
  15. 2400
  16. 600
  17. 400
  18. 1200
  19. 900
  20. 2100
  21. 5000
  22. 700
  23. 1800
  24. 3000
  25. 900
  26. 1300
  27. 900
  28. 1000
  29. 1200
  30. 1000
  31. 5600
  32. 3000
  33. 1800
  34. 1000
  35. 1000
  36. 2800
  37. 3600
  38. 1400
  39. 1400
  40. 1000

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